Heat a large skillet or wok over medium-high heat. Add a tablespoon of vegetable oil.
Once the oil is hot, add the garlic and ginger. Stir-fry for about 30 seconds, until fragrant.
Add the cabbage, carrots, and celery to the skillet. Stir-fry for 3-4 minutes, until vegetables start to soften.
Add the mushrooms and bean sprouts. Continue to stir-fry for another 2-3 minutes.
Pour in the soy sauce and sesame oil. Stir to combine. Remove from heat and let cool slightly.
In a small bowl, whisk together cornstarch and water until smooth to make slurry.
Lay a spring roll wrapper on a dry surface, corner pointing towards you.
Place 2-3 tablespoons of cooled filling in the center.
Fold bottom corner over filling and tuck in.
Fold in left and right sides towards the center.
Brush the top corner of the wrapper with cornstarch slurry.
Roll upwards tightly to seal.
For pan-frying: Heat 1/4 inch vegetable oil, fry spring rolls 2-3 minutes per side until golden. For baking: Preheat oven to 400°F (200°C), brush spring rolls with oil, bake 20-25 minutes, flipping halfway.
Serve immediately with dipping sauce.